There is an urgent need for suitable protective clothing for agricultural pesticide workers. Pesticide exposures are predominantly dermal and pesticide poisonings are a serious occupational hazard. Existing clothing, usually made of rubber or plastic, although effective, is too hot to wear in the southern parts of the United States and present acceptability problems even in northern latitudes during the summer. The usual worker clothing, though preventing direct contact of the chemical with the skin initially, soon becomes saturated with chemicals, particularly when liquid applications are used. The carrier may be water or oil and cloth treated with certain organo-silicone derivatives and related materials are known to have a degree of repellency to water and oils. These studies contemplate using such products to treat textiles in order to provide protection from pesticide exposure. The potential of a silicone treatment of the pesticide workers' clothing to reduce his exposure acquired under normal working conditions will be tested. Three separate but related activities are proposed; these are (1) the field-testing of treated clothing on exposed workers (University of Miami School of Medicine), (2) heat exchange and ergonomic studies (University of Miami School of Engineering), and (3) laboratory clothing studies (Environmental Health Sciences Center, Oregon State University, Corvallis, Oregon). In the field occupational study, using cholinesterase comparisons, urinary pesticide metabolite excretions, and determinations of pesticide residues on the clothing and underclothing of the worker, the effects of silicone treatment of the workers' clothing will be studied. Heat exchange studies will measure the thermal air and water vapor resistance of the silicone treated fabric in the first year, and conduct ergonomic studies in volunteer subjects in the second year. In the laboratory clothing study, the chemical uptake of the pesticide by the clothing will be studied, the effects of laundering tested, and the problems of different textiles when treated by a variety of material measured. Fabric repellence and saturation will be measured in both lab and field studies.